Aluminum alloys in aerospace industry

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Aluminum alloys in aerospace industry

Aluminum alloy is the main material of aerospace and aircraft industry. Compared with the steel used in the manufacture of automobiles, aluminum alloys are cheap and low in density. The relative density is 2.8. Compared with the relative density of steel, which is 7.8, it is about one-third lighter. Although the strength is similar, for aircraft, the material Lightness is the most important, and it has strong corrosion resistance and convenient processing, so aluminum alloy is the most ideal material for manufacturing aircraft.

Hard aluminum can be used to manufacture rivets, aircraft propellers and high-strength parts on aircraft according to the content of its alloying elements; super hard aluminum is a hard aluminum containing zinc, and its hardness and strength are higher than that of hard aluminum. Different varieties of super hard aluminum It is used to manufacture various structural parts and high-load parts, and is one of the important materials in the aviation industry.

What aluminum alloys are used in aerospace?

  • 2024: Aluminum alloy 2024 is the most widely used in aerospace development. The alloy has a high yield strength and is a high-grade alloy with excellent fatigue resistance. It is commonly used in sheet form for the wings and fuselage.
  • 2014: Alloy 2014 is the second most used aluminum alloy in this industry. It is known for its strength and toughness but is susceptible to corrosion. As such, it’s often used inside the framework rather than the shell. One of the other reasons why this alloy is preferred is because it is suitable for arc welding.
  • 5052: This is a non-heat treatable grade of alloy. It provides the highest strength and is highly ductile as well. It can be formed into various shapes and is highly corrosion resistant making it an ideal addition for numerous applications in aerospace.
  • 6061: Grade 6061 is commonly used in light crafts. Its easy machinability and welding are some of the reasons why it’s often preferred for these applications. It is fairly strong and features prominently in the wings and fuselage of the planes.
  • 7050: For its high corrosion resistance and strength in wide sections, grade 7050 is commonly used in the wing skins and fuselage and more so in military crafts. Its high resistance to fractures compared to other alloys is one of the reasons it’s highly regarded in the aerospace industry.
  •  7068: This is one of the strongest alloys in the market, and it has a low mass. It’s perfect for crafts that need to stand up to the tough conditions and is also used in military aircraft.
  • 7075: The strength of grade 7075 is comparable to that of steel thanks to its high levels of zinc. It has impeccable fatigue resistance and is easy to machine. It was a popular choice for planes in World War II and remained frequently featured in some military crafts.
Less common aluminum alloys; Several other aluminum alloys not known to many play a crucial role in the development of the aerospace and aircraft industries.

2219: This aluminum alloy provides maximum strength at high temperatures. It was used successfully for the external fuel tank of the first successfully launched space shuttle Columbia. Its properties include good weldability.

6063: Grade 6063 is commonly used for its aesthetic appeal and not necessarily its structural prowess. It’s commonly used for intricate extrusion but also has a high resistance to fracture and fatigue and is very strong.

7475: Finally, there is aluminum alloy 7475, which is at times found in the fuselage bulkheads of large aircraft. Like others mentioned herein, it’s incredibly strong.

The demand for aluminum in the aerospace will most likely double in the next few years, especially with the newly developed aluminum-lithium alloys that could reduce aircraft weight and improve performance.

Why aluminum alloys are used in aerospace industry?

Why aluminum alloys are used in aerospace industry?

First of all, understand the two types of structural materials used in aerospace vehicles: metal materials and composite materials. Metal materials have mature performance and processing and manufacturing foundation, and have always been the first choice for satellite structural materials; composite materials, as emerging materials, are favored by researchers for their outstanding advantages such as low density and strong designability, and gradually replace metal materials. Trend as the main structural material for satellites.
As the main manufacturing material of spacecraft, aluminum alloy requires a large amount of aluminum alloy materials from fuel tanks, manned cabins (escape cabins), and orbital cabins. So, what are the main aluminum alloys for aerospace?

Aluminum alloy large extruded profiles, aluminum-lithium alloys, aluminum alloy thick plates, and aluminum alloy castings have become the first choice for aerospace aluminum alloys.

The characteristics of metal materials are that they can be welded. They are mainly used in the structure of satellite sealed shells, and are also suitable for load-bearing structural parts such as joints and brackets. Among metal materials, alloy steel is the most widely used structural material in the industry, but in the aerospace field, except for a small number of structures using alloy steel, lighter aluminum alloys, titanium alloys, magnesium alloys, etc. are mainly used. Lightweight alloys have a much lower density with comparable specific moduli.

 

Among the light alloys, aluminum alloys are relatively cheap, have good thermal conductivity, electrical conductivity and corrosion resistance, and are currently the most widely used light metal materials on satellites. Some aluminum alloys also have good low temperature properties, and their strength and plasticity increase with the decrease of temperature. In the classic space shuttle era, the crew compartment, forward fuselage, mid-fuselage, aft fuselage, vertical tail, flaps, elevons and horizontal stabilizer were all made of aluminum alloys. In the United States, 7 series aluminum alloys such as 7075, 7475 and 7055 are mainly studied and applied. Aluminum alloys with these components not only have high strength, but also high toughness, which has always been the goal pursued by aerospace materials researchers in various countries.

In summary, the application of aluminum alloy in the aerospace field is mainly because it is actually an ultra-high-strength deformed aluminum alloy with good mechanical and processing properties, good plasticity after solution treatment, and good heat treatment strengthening effect. Below 150°C (or even higher), it has high strength and good toughness, making it an ideal structural material.

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Author: Mose Li

Author: Mose Li

Director of Project Engineering at 3Q Machining

Materials

The guideline for raw materials, understand more to choose best material for your custom part projects.

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